Piston pump



Aug, 1930. l Y H. FRIBERG A 17,772,137

PI STON PUMP Filed Dec. 1s', 1928 2 sheets-sheet 1 Aug. 5, 1930.

H. FRIBERG PISTON PUMP Filed Dec. 15, 1928 J5 K595i 40 40 4l 42 2 Sheets-Sheet 2 Patented Aug. 5, 1930 UNITED STATES PATENT FFICE.

HJALMAR FRIBERG, OF ISITOCKHOLM, SWEDEN, ASSIGNOR TO AKTIEBOLAGET FRI- BERGS H'OGVACUUMPUMP, OF STOCKHOLM, SWEDEN PISTON PUMP Application led December 13, 1928, Serialv No. 325,867, and in Sweden December 22, 1927.

This invention relates to piston pumps especially for rarefying or compressing air or other gaseous uids.

Piston pumps for such purposes are known which are provided with spring-loaded suction and pressure valves combined with controlling means in mechanical connection with the piston or its driving means and adapted to relieve the valves from the pressure of the springs when the piston is in or near to its end positions, the valves being in such manner positively o erated to open and close the inlets and out ets in due time. Such pumps have the advantage that the clearance of the pump cylinder can be reduced practically to nil, and they may thus be used to create very high vacua or very high pressures with one cylinder only. A drawback of such pumps as hitherto constructed was, however, that they could not advantageously be carried out with doubleacting pistons.

The chief object of this invention is to improve piston pumps of the kind above referred to so as to make it possible to construct them double-acting while maintaining the advantage of a minimal clearance of the cylinder at both ends of the latter.

The invention consists, chieiiy, in a douhleacting piston pump, comprising a cylinder, spring-loaded loose covers atV both ends of said cylinder forming the outlet valves of the pump, al hollow piston having inlet valves in both ends, and a hollow piston rod connecting the interior of the piston with the suction. conduit of the pump.

Another object of the invention is to provide limproved means for loading and un-A loading the inlet'and outlet valves of the pump as will be set forth in detail in the following description of the invention.

In the accompanying drawings I have shown, in partV diagrammatically, one embodiment of my invention.

Fig. 1 is a longitudinal central section of double-acting vacuum pump according to the invention, the piston being shown in one of its endpositions.

" Fig. 2shows on a larger'sca-le a longitudi- Fig. 4 is a similar view to thatshown in Fig. 2 with the piston shown in a position in which it is at a distance from the right end of the cylinder.

Referring no-w to the drawings, 1 is the pump cylinder and 2 the pump piston which in usual manner is provided with tightening rings 3 disposed in grooves in the mantle surface of the piston. The piston 2 is adapted to be driven from the main shaft 4 by means of a disc crank 5, a connectingrod 6 and a link 8 journalled on a pin 7 and being at its free end provided with'a toothed bow 9 engaging a rack 10 secured to one end of the vpiston rod 11 and forming an extension of the latter. The piston rod 11 which is composed of two parts, one on each side of the piston 2, is hollow, its channel being in open connection .with the hollow 12 of the piston on one side and with a'chamber 13 in an eX- tension 14 of the pump casing on the other side. VThe extension 14 is provided with a flanged socket 15 adaptedv to he connected with the vessel to be evacuated. Outside. the open plane ends of the cylinder 1 covers 16, 16 are provided which form the pressure or outlet valves of the pump and for Vsuch purpose are movable to and from the open and are connected with each other' by a chan-l nel 19 provided with a'llanged socket 20. The latter is, when the pump isused for evacuating purposes,inconnection with the open air while it is connected with the Vpressure conduit of the pump when the pump is acting as a compressor'. In each end` wall of thek piston 2 two suction or inlet valves 21 Vand 22 respectively areprovided, said valves being loaded by springs 23and 24 respectively tending to close the valves.' The valve stems are guided yhy straps 23a and 24a-repressure valves from their loadsV .in thedesired moments yin relation Vto the fof two springs 40 er than V.the springs 23 and 24 ofV spectively and are at their inner ends provided with heads 25 and 26 respectively.

The cylinder covers 16, 16 forming the pressure valves are each loaded by a lami-V nated plate spring 27 secured to a swingable arm 29 journalled on a pin 28 and having an inner furcated end which engages the outer side of the cover 16. The outer ends ofthe springs 27 engage recesses in two adf justableiheads 30.011 a push rod 3 1 Vj ournalled in guides 32 in such .manner that iteanbe moved parallelly to the piston. rEhe push rod -31which in this case forms a member controlling the load of the pressure valves 16 is by means of a lin-lr jour-nalled on a pin 34, and a link ,36 connected to the arm 8 in such manner that it is moved to the right, Fig. 1, whenthe piston 2 moves to the left, ,and vice-versa. `When the push rod 31 is moved to the right, 1, the right spring 27 will press the right cover or pressure valve 16 against its seat, i. e. the right end of the cylinder 1, while the left pressureval-ve 16 simultaneously is relieved from the load ofthe left spring 27. W hen the rod 27 is moved to the left, the left spring f 27 will press the left pressure valve 16 against its seat while the right pressure valve 16 at the saine time is relieved from the load vof `the right spring ,27l vBy Yadjusting' the heads 30 on the rod 31 and the .connecting poi-ntof the .link 36 with the arm 8 in suitable mannerA it is possible to attain .that the relieving .of .the takes. place movements of the piston 2.

The Vcontrolling members of the suction 4valves 21 and22 consist in the embodiment shown yof two levers 37 rotatably .journalled .on two parallel pins 38 secured in varms 39 inthe interior of the piston. The outer end of said levers are coupledV together by .means which are essentially strong- .the suction valves. The levers 37 `are shifted into the position shown with full lines in Fig. V2 inimediately before the piston 2 reaches its wall 43 vof the chamber1Qi.' yThe v outer ends vof the 4levers 37 are in this position in een-tact with the stern heads 26er" the suctionvalves :22 and openby. .the Vaetion of the strong :springs vjsaidvalves as soon as the` piston .begins itsmovementto the Vleft (see The :levers 13.7 arelthereafter immediately .be-

fore the {piston `reaches its `left V end position shifted tothe position shown `bydotleld" lines ing theiouterends ofthe .levers in Fig..-2, by-means of a head r44 on a lfir sleeve 45 secured to .the wa-ll 43 and .sur-

rounding the vro d42. By said lattershift- .371' are brought into 1Contact;.with .the stem heads 25 of the Snotion valvesj21 andopen thejlatterbynieans '33, a lever '35 rotatably i the springo pv di' rod42 andthe sleeve 45 and thus also the members 41 and 44 can be adjusted so that the shifting ofthe levers takes place in the desired moments in relation to the movements of the piston 2.

.ln the position shown in Figs. 1 and 2 the vpiston 2 in its right endposition iny which the right cylinder cover or pressure valve 16 is somewhat lifted from theright end of the cylinder 1 and closely fits to the plane right side ofthe piston The suction valves 22 are, therefore, held closed though the springloaded levers 37 engage the spindle heads llhen thepiston 2 then begins its movement to the left the rod 31 is `at moved to the right. yThe right spring 27 Fig. 1, will then exert a pressure on the right cylinder cover 16 so that the latter is caused to follow .the piston until it is pressed againstv the right end of the cylinder 1. Thespring load is thus brought to act o n the right pressure valve 16 immediately when the ypiston begins to move towards the left so that said pressure valve is .once safely closed. lmmec iately after the closing of the right cover or valve 1-6 vthe springs 40 aeting on the 'levers 37 open at the continued movement ofthe piston 2 to the left the suction val-ves y22 v(see liig. 4) while overcoming the tension of the weaker valve springs T he suction valves are thus positively opened vwithout the asfV s tance of anyv suction action thereon by the i' Asten. During the continued movement of ythe piston 2te the left the air can thenbe sucked into the right chamber of the cylinder 1 from the vessel to lee/evacuated, said ,air `flowing through ythe,socket 15, the cham ber 18, the hollow Vpiston rod 11, the chamber 1 2 and the open suction valves 22. At theA into the open air through thechannel 19 and the socket 20;

VV1mmedi'atelyf*. before the .piston 2 reaches the left vend position ofitsstrokethe'levers i 125' 37 hit the head 44 and are-*by saidhead and gs 40 shifted/into the position shown d lines in .lfigu2whereupon A.thelevers 37 will resten thestemheads2g5 of thesncf tion valves 21. lSaid Valves arie, however, not

.immediately .opened by.. the .pressurelrofj the thev same timey ioisf iao springs 40 in as much as they already before the shitting of the levers 37 had come into engagement with the lett cylinder cover 16. Vilhen the pump piston 2 inally reaches its left end position it has lifted the lett cylinder cover 16 somewhat from the lett-'end or the cylinder wall. In this moment the left cover 1G rests against the piston 2 in the same manner betore the right cover rested against the piston 2). When the piston 2 then. begins its stroke towards the right the rod 31 is simultaneously moved to the left thus causing the left spring 27 (Fig. 1) to exert a pressure against the left cylinder cover 16 so that the latter follows the piston until it is pressed against the left end of the cylinder 1. The spring load is accordingly caused to act on the left pressure valve 16 immediately when the piston begins to move towards the left so that said pressure valve is at once closed. Immediately thereafter the springs Al() open by means of the levers 37 the suction valvesrQl without any suction action of the piston being necessary for such purpose. During the movement ot the piston towards the right air is sucked in through the socket 15, the chamber 13, the hollow piston rod 11, the chamber 12 and the open suction valves 21 into the left chamber of the cylinder. At the same time the air contained in the right chamber of the cylinder is forced out between the right end of the cylinder wall and the right cylinder cover 16 which now is relieved from its spring-load, whereupon said air escapes through the channel 19 and the socket 2O to the open air. The pump described is accordingly double-acting and has` also the advantage that it has practically no clearance in the cylinder.

rhe embodiment above described and shown in the drawing is only an example and can` of course, be modified in several respects without departing from the principle of the invention. The means illustrated for driving the piston are not essential for the invention. For the toothed bow 9 and the rack 10 other equivalent means such as a steel band connection between the rod 11 and a smooth driving bow may be used. Vhen the pump is to be used as compressor, the socket 20 is connected to the vessel inV which the gas is to be compressed. In such case it is, of course, necessary to tighten the caps 18 at the pins 28 so that the gas is prevented from leaking at said place.

What I claim is Y l. A double-acting piston pump, comprising a cylinder having open plane ends, springloaded loose covers adapted to close said ends and forming outlet valves, a hollow piston, spring-loaded suction valvesin the end walls of said piston, means for positively opening some of said suction valves against the action of their spring-load when the piston is in or near to any of its end positions, and a hollow piston rod connecting the interior of the piston with the suction conduit of the pump.

l2. A double-acting piston pump, compris ing a cylinder, spring-loaded loose covers at the ends of said cylinder forming outlet valves, a hollow piston, spring-loaded suction valves in the end walls of said piston, and swingable levers in the interior of the piston adapted to open some of the suction valves against the action of their spring-load when the piston is in or near to any of its end positions.

3. A double-acting piston pump, comprising a cylinder, spring-loaded loose covers at the ends of said cylinder forming outlet valves, a hollow piston, spring-loaded suction valves in the end walls of said piston,spring loaded levers rotatably journalled in the interior of the piston, and fix stops adapted to cooperate with said levers so as to open some of the suction valves when the piston is in or near to any of its end positions.

el. A double-acting piston pump, compris` ing a cylinder, spring-loaded loose covers at the ends of said cylinder forming outlet valves, a hollow piston, spring-loaded suction valves in the end walls of said piston, spring-loaded levers rotatably journalled in the interior of the piston, fix stops adapted to cooperate with said levers so as to open 'some of the suction valves when the piston is in or near to any of its end positions, and means for adjusting the position of said stops.

5. A double-acting piston pump, comprising a cylinder, loose covers at the ends of said cylinder forming outlet valves, springs adapted to exert a pressure on said covers, a hollow piston, suctionvalves in the end walls of said piston, driving means for the said piston and means operated from said driving means and adapted to operate the springs of the end covers so as valternately to load and unload said covers.

6. A double-acting piston pump, comprising a cylinder, loose covers at the ends of said cylinder forming outlet valves, springs adapted to exert a pressure on said covers, a y Y hollow piston, driving means for said piston, a push rod mechanically connected to said driving meansand adapted to operate said springs so as alternately to load and unload said covers, and means for adjusting the operation of said push rod.

In testimonyk whereof I have signed my name.

HJALMARA FRIBERG. 

